Encoded stream generating apparatus and method, data transmission system and method, and editing system and method

ABSTRACT

A method and apparatus for generating an encoded data stream representing a number of pictures or frames and having a number of layers including a picture layer in which time code information attached to the original data is described or inserted therein for each picture. Such time code information may be inserted into a user data area of the picture layer of the encoded data stream.

This application is a division of Ser. No. 09/317,329, filed May 24,1999, which is a continuation of PCT/JP98/04292, filed Sep. 25, 1998.

BACKGROUND OF THE INVENTION

The present invention relates to an apparatus and method for generatingan encoded stream having a time code for each picture from source datasuch as video data and/or audio data, a data transmission system andmethod for transmitting the encoded stream with the time code addedthereto for each picture, and an editing system and method for editingdata by use of the time code added to the encoded stream.

Recently, the technique for the MPEG (Moving Picture Experts Group)standard for compression-encoding of video data and audio data has beendeveloped. A digital transmission system for transmittingcompression-encoded data for broadcasting to a receiving end accordingto the MPEG standard has been proposed. A recording and reproductionsystem has also been proposed, in which the video data and audio datacompression-encoded according to the MPEG standard are recorded in andreproduced from a storage medium such as a DVD (digital video disk)which is an optical disk capable of recording a large capacity ofdigital data.

Further, in applications employing a plurality of types of encodedstreams (hereinafter sometimes referred to as the stream or streams)obtained by encoding video data and audio data and other dataindividually, the streams are integrated for transmission. A digitaltransmission system may be used in such a case. Specifically, in adigital data transmission system, a plurality of types of streams aremultiplexed in a time division manner in a form suited to a streamtransmission medium (storage medium and transmission path) so as togenerate a transport stream which may be transmitted to the receivingend. At the receiving end, on the other hand, the transport stream fromthe transmitting end is received and demultiplexed into video or audiodata and individually decoded.

The data (video data and audio data) handled in such a transmissionsystem are generally accompanied by time information called a time code.The time code is time information defined by SMPTE, and means “Time AndControl Data”. Specifically, the time code is data representative offrames, seconds, minutes and hours.

In the digital data transmission system, time information may be managedbased on a unique time concept such as STC (System Time Clock, which isreference time information), PTS (Presentation Time Stamp, which is timemanagement information for reproduced output), DTS (Decoding Time Stamp,which is time management information for decoding), SCR (System ClockReference, which is a time reference value) and PCR (Program ClockReference, which is a time reference value for a program). In otherwords, the timings of an encoded stream encoded according to the MPEGstandard is managed by time information which is completely differentfrom the time code described above.

Specifically, in a baseband system in which baseband video data arehandled and processed, the processing timings of the baseband video dataare managed using the time code. On the other hand, in the encodingsystem for handling and processing an encoded stream, the processingtimings are managed based on unique time information such as STC, PTS,DTS, SCR or PCR described above.

The stream encoded by the MPEG standard represents a sequence layer, aGOP (Group Of Picture) layer, a picture layer, a slice layer, amacroblock layer and a block layer. Also, according to the MPEGstandard, a function called the group_of_picture_header( ) is definedfor describing the header data of the GOP layer. As the header data ofthe GOP layer, this group_of_picture_header( ) function has dataincluding a 32-bit group_start_code, a 25-bit time_code, a one-bitclosed_gop and a one-bit broken_link. The group_start_code is the datafor indicating the start of the group of picture header and a time codeindicating the time taken from the head of the sequence of the headpicture of the GOP. The closed_gop is flag data indicating that theimage in the GOP can be reproduced independently of GOPs. Thebroken_link is flag data indicating that the B picture at the head inthe GOP cannot be accurately reproduced for editing or the like.

The time_code described as header data of the GOP layer by thegroup_of_picture_header( ) function defined by the MPEG standard is dataindicating the time code taken from the head of the sequence of theprogram transmitted. As such, the original time code of or attached tothe original material data is not used. For example, if the originaltime code supplied from an external unit and attached to the head frameof the original material data is “01:30:00:00”, once the head frame ofthe original material data is encoded, the time_code described as theheader data of the GOP layer of the encoded stream becomes“00:00:00:00”. Also, even when the original time code attached to eachframe of the original material data is a discontinuous time code, thetime_code described as the header data of the GOP layer of the encodedstream is a sequential time code. In other words, the original time codeattached to the original material data is not always coincident with thetime code described as the header data of the GOP layer of the encodedstream.

Also, the time_code described by the group_of_picture_header( ) functionof the MPEG standard is data described as header data of the GOP layer.Therefore, according to the MPEG standard, the time code can bedescribed only for each GOP. In other words, according to the MPEGstandard, the time code can be transmitted for each GOP by describingthe time code in the GOP layer of the encoded stream. Since the MPEGstandard does not define or describe the time code for each frame (eachpicture), the time code cannot be transmitted for each picture.

As a result, the time code information is not attached for each picturein the encoded stream of the MPEG standard. Accordingly, if originalmaterial data is encoded according to the MPEG standard, the originaltime code attached to each frame of the original material data cannot betransmitted to the receiving end.

Consequently, the original time code attached to the original materialdata cannot be used for editing at the receiving end, nor may arecording medium be produced which is identical to a recording mediumrecorded with the original material data in a manner corresponding tothe original time code.

OBJECTS AND SUMMARY OF THE INVENTION

An object of the present invention is to provide an apparatus and methodfor generating an encoded stream having time code informationcorresponding to that of the original material data for each picture(each frame), and a system and method for transmitting such encodedstream.

Another object of the present invention is to provide an editing systemand method wherein an editing process may be performed at a receivingend by utilizing time code information corresponding to that of theoriginal material data which was transmitted together with an encodedstream to the receiving end.

According to an aspect of the present invention, an apparatus isprovided for generating an encoded stream from source video data,wherein the source video data represents a number of pictures or framesand includes original time code information corresponding to eachpicture or frame. The apparatus comprises an encoding device forencoding the source video data to generate the encoded stream having anumber of layers including a picture layer, and a device for insertingthe original time code information into a user data area of the picturelayer of the encoded stream.

According to another aspect of the present invention, a datatransmission system for transmitting source video data is provided. Suchsystem comprises a data supply device operable with a first recordingmedium for storing source video data and time code information attachedto the source video data, wherein the time code information isassociated with each video frame of the source video data; an encodingdevice for generating an encoded stream having a plurality of layersgenerated by encoding the source video data, and for describing the timecode information attached to each frame of the source video data into apicture layer among the plurality of layers; a transmission device fortransmitting the encoded stream; a decoding device for decoding theencoded stream transmitted through the transmission means and extractingthe time code information from the picture layer of the encoded streamby parsing the syntax of the encoded stream; and a data recording devicefor recording the data decoded by the decoding device and the time codeinformation extracted by the decoding device in a manner associated witheach other onto a second recording medium so as to obtain the same dataas on the first recording medium.

According to another aspect of the present invention, an editing systemfor editing source video data is provided. Such system comprises adevice for generating an editing list based on editing points set in thesource video data; an encoding device for generating an encoded streamhaving a plurality of layers generated by encoding the source videodata, wherein time code information attached to each frame of the sourcevideo data is described in a picture layer among the plurality oflayers; a transmission device for transmitting the encoded stream; adecoding device for decoding the encoded stream transmitted through thetransmission device and extracting the time code information from thepicture layer of the encoded stream by parsing the syntax of the encodedstream; and an editing device for editing the video data decoded by thedecoding device based on the time code information obtained by parsingthe syntax of the encoded stream and the editing list.

According to another aspect of the present invention, an editing systemfor editing an encoded stream obtained by encoding source video data isprovided. Such system comprises a device for generating an editing listbased on editing points set in the source video data; an encoding devicefor generating an encoded stream having a plurality of layers generatedby encoding the source video data, wherein time code informationattached to each frame of the source video data is described in apicture area among the plurality of layers; and an editing device forediting the encoded stream based on the time code information obtainedby parsing the syntax of the encoded stream and the editing list.

According to another aspect of the present invention, an editing systemfor editing an encoded stream is provided. Such system comprises abaseband system for generating an editing list based on editing pointsset by processing baseband source video data; and an encoding system forgenerating an encoded stream having a plurality of layers generated byencoding the source video data, wherein time code information attachedto each frame of the source video data is described in a picture layeramong the plurality of layers, and the encoded stream is edited at thestream level based on the time code information obtained by parsing thesyntax of the encoded stream and the editing list generated in thebaseband system.

In the present invention, data indicative of the time code of the sourcevideo data is arranged in a user data area of a picture layer of theencoded stream.

In the present invention, an encoded stream having the time code foreach frame of the source video data in the picture layer of a pluralityof layers maybe transmitted. The transmitted encoded stream may bedecoded and by analyzing the syntax of the encoded stream, the time codemay be extracted from the picture layer of the encoded stream, and thedecoded data and the extracted time code information may be recorded ina recording medium in a manner associated with each other, therebyproducing a recording medium having recorded therein the same data asthe recording medium which supplied the data at the data supply side.

In the present invention, an editing list may be generated based onediting points set in the source video data and an encoded stream may begenerated having the time code for each frame of the source video datain the picture layer of a plurality of layers and transmitted. Thetransmitted encoded stream may be decoded, the time code extracted fromthe picture layer of the encoded stream by analyzing the syntax of theencoded stream, and the decoded source video data edited based on theobtained time code and the editing list.

In the present invention, an editing list may be generated based onediting points set in the source video data and an encoded stream may begenerated having the time code for each frame of the source video datain the picture layer of a plurality of layers. The encoded stream may beedited based on the editing list and the time code obtained by analyzingthe syntax of the encoded stream.

In the present invention, an editing list may be generated based onediting points set by processing baseband source video data. Also, anencoded stream may be generated having the time code for each frame ofthe source video data described in the picture layer of a plurality oflayers, and the encoded stream may be edited at a stream level based onthe time code obtained by analyzing the syntax of the encoded stream andthe generated editing list.

The above and other objects, features and advantages according to thepresent invention will be apparent from the following detaileddescription of the illustrated embodiments when read in conjunction withthe accompanying drawings in which corresponding components areidentified by the same reference numerals.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram of a digital data transmission system having anencoded stream generating device according to an embodiment of thepresent invention;

FIG. 2 is a diagram of a digital data processing system having anencoded stream generating device according to another embodiment of thepresent invention;

FIG. 3 is a diagram of a video encoder of the systems of FIGS. 1 and 2;

FIG. 4 is a diagram of an audio encoder of the systems of FIGS. 1 and 2;

FIG. 5 is a diagram of a configuration of the AC3 encoder shown in FIGS.1 and 2;

FIG. 6 is a diagram showing the syntax of an encoded stream based on aMPEG standard;

FIG. 7 is a diagram of the syntax of a portion of FIG. 6;

FIG. 8 is a diagram of the syntax of a portion of FIG. 7;

FIG. 9 is a diagram showing the syntax of a portion of FIG. 8;

FIG. 10 is a diagram to which reference will be made in explaining thedata structure of an encoded stream according to a MPEG standard;

FIGS. 11A and 11B are diagrams of the data structure of time codeinformation described in a user data area of a picture layer;

FIG. 12 is a diagram of a data identification code of the informationdescribed in the user data area of the picture layer;

FIG. 13 is a diagram to which reference will be made in explaining afirst method of adding a time code to the encoded stream;

FIG. 14 is a diagram to which reference will be made in explaining asecond method of adding a time code to the encoded stream;

FIG. 15 is a diagram to which reference will be made in explaining thedata structure of the audio elementary stream according to a MPEGstandard;

FIGS. 16A and 16B are diagrams to which reference will be made inexplaining the phase difference between the video frame and the audioframe; and

FIG. 17 is a diagram to which reference will be made in explaining thedata structure of an AC3 stream according to an AC3 standard.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

An encoded stream generating apparatus and method according to anembodiment of the invention will now be described with reference to theaccompanying drawings.

FIG. 1 illustrates a digital data transmission system having an encodedstream generating apparatus according to an embodiment of the invention.The digital data transmission system of FIG. 1 includes a transmissionsystem 1, a receiving system 3 and a transmission line 2 between them.Various forms of the transmission system 1 and the receiving system 3may be possible. For example, the transmission system 1 may be a relayvehicle located in the field, and the receiving system 3 may be a mainor local broadcasting station. As another example, the transmissionsystem 1 may be a main broadcasting station, and the receiving system 3may be a local station. The transmission system 1 and the receivingsystem 3 will be explained below.

The transmission system 1 generally includes a baseband system 1A forprocessing and handling baseband video data and baseband audio data, andan encoding system 1B for handling the encoded stream. The basebandvideo data and the baseband audio data referred to herein represent datawhich is not compression-encoded.

The baseband system 1A of the transmission system 1 may include a VTR 12for receiving a tape having recorded therein original material datapicked up by a video camera or the like in the field and reproducing theoriginal data from the tape and recording information in the tape, anA/V server 13 having a randomly-accessible recording medium forreproducing the original material data from the randomly-accessiblerecording medium and recording information in the recording medium, aneditor 14 for generating an editing list or edit decision list (EDL)using the original material data recorded in the tape of the VTR 12 andthe recording medium of the A/V server 13, and a router 15 for routingvideo data DV and audio data DA reproduced from the VTR 12 and videodata DV and audio data DA reproduced from the A/V server 13 andoutputting them to a predetermined block.

The encoding system 1B of the transmission system 1 may include a videoencoder 16 for encoding the video data DV supplied as original dataaccording to a MPEG video standard and outputting a video elementarystream (video ES), an audio encoder 17 for encoding the audio data DAsupplied as original data according to the MPEG standard and outputtingan audio elementary stream (audio ES), an AC3 encoder 18 for encodingthe audio data DA supplied as original data according to an AC3 standardand outputting a private elementary stream (private ES), packetizers 19,20, 21 for respectively packetizing the elementary streams outputtedfrom the video encoder 16, the audio encoder 17 and the AC3 encoder andoutputting packetized elementary streams (PES), and a transport streammultiplexer (TSMUX) 22 for generating a transport stream (TS) bymultiplexing the packetized elementary streams from the packetizers 19,20, 21.

The digital data transmission system of FIG. 1 may further include a CPU11 for controlling and managing each block of the baseband system 1A andthe encoding system 1B. The CPU 11 receives the time code TCcorresponding to each frame of the video data and the audio datareproduced from the VTR 12 or the A/V server 13, converts the time codeTC into a predetermined format and supplies the same to the videoencoder 16, the audio encoder 17 and the AC3 encoder.

On the other hand, the receiving system 3 of FIG. 1 may include adecoding system 3A for processing and handling the encoded stream, and abaseband system 3B for processing and handling decoded baseband videodata and decoded baseband audio data.

The decoding system 3A of the receiving system 3 may include a transportstream demultiplexer (TSDEMUX) 32 for receiving the transport streamtransmitted from the transmission system 1 through the transmissionmedia 2 and demultiplexing it into a video packetized elementary stream(video PES), an audio packetized elementary stream (audio PES) and aprivate packetized elementary stream (private PES); depacketizers 33,34, 35 for depacketizing the video packetized elementary stream, theaudio packetized elementary stream and the private packetized elementarystream outputted from the transport stream demultiplexer 32 andoutputting a video elementary stream (video ES), an audio elementarystream (audio ES) and a private elementary stream (private ES); a videodecoder 36 for decoding the video elementary stream outputted from thedepacketizer 36 and outputting baseband video data DV; an audio decoder37 for decoding the audio elementary stream outputted from thedepacketizer 34 and outputting baseband audio data DA; and an AC3decoder 38 for decoding the private elementary stream outputted from thedepacketizer 35 and outputting baseband audio data DA.

The baseband system 3B of the receiving system 3 may include a router 39for receiving the video data DV outputted from the video decoder 36, theaudio data DA outputted from the audio decoder 37 and the audio data DAoutputted from the AC3 decoder 38 and routing them to a predeterminedprocessing device; a VTR 40 for receiving the video data DV and theaudio data DA outputted from the router 39 and recording them in atape-like recording medium; an A/V server 41 for receiving the videodata DV and the audio data DA outputted from the router 39 and recordingthem in a randomly-accessible recording medium; and an editor 42 forediting the video data DV and the audio data DA stored in the VTR 40 andthe A/V server 41. Also, the video decoder 36, the audio decoder 37 andthe AC3 decoder 38 may extract the time code information described inthe elementary streams by analyzing the syntax of the respectiveelementary streams.

Further, the receiving system 3 may include a CPU 31 for controlling andmanaging the devices or circuits in the decoding system 3A and thebaseband system 3B. This CPU 31 receives time code data TC outputtedfrom the video decoder 36, the audio decoder 37 and the AC3 decoder 38,and may output the time code TC therefrom to the VTR 40, the A/V server41 and/or the editor 42.

Devices or circuits of the transmission system 1 and the receivingsystem 2 will now be further described.

The VTR 12 and the A/V server 13 have recorded therein the basebandvideo data and the baseband audio data as original data. Further, thevideo data and the audio data recorded in the VTR 12 and the A/V server13 are related to the original code for each frame. In other words, atime code is attached to or associated with each frame of the video dataand the audio data.

The time code may be two types, that is, LTC (Longitudinal TimeCode/Linear Time Code) and VITC (Vertical Interval Time Code). The LTCis a time code recorded in a time code track formed longitudinally ofthe tape. The VITC is a time code inserted in the vertical blankingperiod of the video signal. In the situation in which a reproductionhead accesses the tape at high speed as in so-called shuttlereproduction, the time code may be read from the LTC. In the situationin which the reproduction head accesses the tape at very slow speed asin still reproduction, the time code may not be read from the LTC.However, the time code may be read from the VITC in the situation inwhich the reproduction head accesses the tape at very low speed, whilethe time code may not be read from the VTC in the situation in which thereproduction head accesses the tape at high speed. Accordingly, both LTCand VITC have advantages and disadvantages. Therefore, similar time codeinformation may be recorded in the tape as LTC and VITC and, at the timeof reproduction, the time code may be read as either LTC or VITC.

According to an embodiment of the present invention, the VTR 12 and theA/V server 13 have recorded therein two types of time codes, LTC andVITC, in a predetermined format.

When reproducing the original video data and the original audio datafrom the VTR 12 and the A/V server 13, the time code TC corresponding tothe particular original video data and the original audio data isoutputted.

The editor 14 may access the original video data and the original audiodata recorded in the VTR 12 and the A/V server 13, and set editingpoints such as an in-point and an out-point in the original video dataand the original audio data. The in-point may be a time code indicatingthe edit starting point, and the out-point may represent the time codeindicating the edit end point. When the editor sets a plurality ofediting points in the original video data and the original audio data byoperating the editor 14 in such a manner as to select only a desiredscene or scenes, an editing list (EDL) may be generated in accordancewith the set editing points. This editing list is simply a time codelist based on the time code(s) of the set in-point(s) and the timecode(s) of the set out-point(s). The video data DV and the audio data DAoutputted from the A/V server 13 are not those edited according to thisediting list, but the original video data and the original audio datanot edited. In an embodiment of this invention, the original video dataand the original audio data are edited according to an editing listgenerated by the editor 14, and the editing process for generatingedited video data and edited audio data is performed by the editor 42 ofthe receiving system 3.

The router 15 is a circuit for routing the original video data DV andthe original audio data DA reproduced from the VTR 12 and the A/V server13 and supplying them to a predetermined processor. For example, theoriginal video data DV is routed in such a manner as to be supplied tothe video encoder 16, and the original audio data DA is routed in such amanner as to be supplied to the audio encoder 17 or the AC3 encoder 18.

The video encoder 16 is a circuit for generating an encoded stream (alsocalled a video elementary stream) by compression-encoding the receivedoriginal video data DV in accordance with the MPEG standard. Also, thevideo encoder 16 receives the original time code TC corresponding to theoriginal video data DV from the CPU 11 for each frame, and describes orarranges the time code in a user data area of a picture layer of theencoded stream.

The audio encoder 17 is a circuit for generating an encoded audio stream(also called an audio elementary stream) by compression-encoding thereceived original audio data DA in accordance with the MPEG standard.Also, the audio encoder 17 receives the original time code TCcorresponding to the original audio data DA for each frame from the CPU11, and describes or arranges the time code TC in the encoded stream.

The AC3 encoder 18 is a circuit for generating an encoded private stream(also called a private elementary stream) by compression-encoding thereceived original audio data DA according to the AC3 standard. Also, theAC3 encoder 18 receives the original time code TC corresponding to theoriginal audio data DA for each frame from the CPU 11, and describes orarranges the particular time code TC in the encoded stream.

The arrangement of the time code TC in the encoded stream will be morefully described hereinafter.

The packetizers 19, 20, 21 receive the video elementary stream outputtedfrom the video encoder 16, the audio elementary stream outputted fromthe audio encoder 17 and the private elementary stream outputted fromthe AC3 encoder 17 and packetize them so as to have the form of apacketized elementary stream standardized for digital video broadcasting(DVB). The packetizer 19 outputs the packetized video elementary streamto the transport stream multiplexer 22 as a video packetized elementarystream; the packetizer 20 outputs the packetized audio elementary streamto the transport stream multiplexer 22 as an audio packetized elementarystream; and the packetizer 21 outputs the packetized private elementarystream to the transport stream multiplexer 22 as a private packetizedelementary stream.

The transport stream multiplexer 22 decomposes or processes the videopacketized elementary stream, the audio packetized elementary stream andthe private packetized elementary stream into units of transport streampackets, and multiplexes the packets to generate a transport stream.

The transport stream demultiplexer 32 demultiplexes the transport streamtransmitted through the transmission media 2 into the video packetizedelementary stream, the audio packetized elementary stream and theprivate packetized elementary stream, outputs the video packetizedelementary stream to the depacketizer 33, outputs the audio packetizedelementary stream to the depacketizer 34, and outputs the privatepacketized elementary stream to the depacketizer 35.

The depacketizer 33 depacketizes the video packetized elementary streamand outputs the video elementary stream to the video decoder 36; thedepacketizer 34 depacketizes the audio packetized elementary stream andoutputs the audio elementary stream to the audio decoder 37; and thedepacketizer 35 depacketizes the private packetized elementary streamand outputs the private elementary stream to the AC3 decoder 38.

The video decoder 36, prior to decoding the received video elementarystream, parses and analyzes the syntax of the video elementary stream.As a result of such, parsing and analyzing of the syntax of the encodedstream, encoding parameters such as the picture type, the predictionmode, the motion vector, the quantization step and the DCT modedescribed in the stream with the picture layer and the macroblock layerof the stream as data elements may be extracted from the encoded stream.The syntax of the encoded stream is analyzed so as to perform a decodingprocess which corresponds to the encoding process performed in theencoder. According to an embodiment of the present invention, whenanalyzing the syntax of the encoded stream, the time code described foreach picture in the user data area of the picture layer is extracted.The video decoder 36, in accordance with the various encoding parametersextracted from the stream, decodes the encoded stream and supplies thedecoded video data DV to the router 39. Further, the video decoder 36supplies the time code TC to the CPU 31 for each frame extracted fromthe encoded stream.

The audio decoder 37, prior to decoding the received audio elementarystream, parses and analyzes the syntax of the audio elementary stream.As a result of such parsing and analyzing of the syntax of the encodedstream, the encoding parameters described in the stream may be extractedfrom the stream. According to an embodiment of the present invention,the time code information described in the encoded stream is extractedfor each frame when analyzing the syntax of the particular encodedstream. The audio decoder 36 decodes the encoded audio stream inaccordance with the encoding parameters extracted from the stream, andsupplies the decoded audio data DA to the router 39. Further, the audiodecoder 37 supplies the time code TC for each frame extracted from theencoded stream to the CPU 31.

The AC3 decoder 38, prior to decoding the received private elementarystream, parses and analyzes the syntax of the private elementary stream.As a result of such parsing and analyzing of the syntax of the encodedstream, the encoding parameters described in the stream may be extractedfrom the stream. According to an embodiment of the present invention,the time code information described in the encoded stream is extractedwhen analyzing the syntax of the particular encoded stream. The privatedecoder 38 decodes the encoded private stream in accordance with theencoding parameters extracted from the stream, and supplies the decodedaudio data DA to the router 39. Further, the AC3 decoder 38 supplies thetime code TC for each frame extracted from the encoded stream to the CPU31.

The baseband video data DV or the baseband audio data DA outputted fromvideo decoder 36, the audio decoder 37 and the AC3 decoder 38 aresupplied to the VTR 40 or the A/V server 41 through the router 39.

The CPU 31 receives from the video decoder 36 the time code TCcorresponding to each frame of the video data DV outputted from thevideo decoder 36, receives from the audio decoder 37 the time code TCcorresponding to each frame of the audio data DA outputted from theaudio decoder 37, and receives from the AC3 decoder 38 the time code TCcorresponding to each frame of the audio data DA outputted from the AC3decoder 38. Further, the CPU 31 supplies the VTR 40 and the A/V server41 with the time code TC corresponding to the baseband video data DV andthe baseband audio data DA supplied to the VTR 40 or the A/V server 41,based on the time code TC received from the video decoder 36, the audiodecoder 37 and the AC3 decoder 38.

The VTR 40 or the A/V server 41, when recording the baseband video dataDV and the baseband audio data DA supplied thereto from the router 39 ina recording medium, records the time code TC supplied from the CPU 31 byrelating it to each frame of the video data DV and the audio data DA. Asan example, consider the situation in which the video data DV and theaudio data DA are recorded in a tape in the VTR 40. In such situation,the VITC contained in the time code TC supplied from the CPU 31 may beinserted in the blanking period of the video data DV and recorded in theslant tracks on the tape while at the same time recording the LTCcontained in the time code TC supplied from the CPU 31 in thelongitudinal tracks on the tape.

Consequently, the recording media of the VTR 40 and the A/V server 41have recorded therein the video data, the audio data and time code whichare respectively identical to the original video data, the originalaudio data and original time code recorded in the recording medium ofthe VTR 12 and the recording medium of the A/V server of thetransmission system 1.

The editor 42 receives an editing list transmitted thereto by way of atelephone line or the like from the editor 14 of the transmission system1, and in accordance with the editing list, edits the video data DV andthe audio data DA recorded in the VTR 40 and the A/V server 41. However,even in the absence of the editing list from the editor 14 of thetransmission system 1, similar editing processing may be performed inthe editor 42 using the time code recorded in the VTR 40 and the A/Vserver 41, in view of the fact that the video data, the audio data andthe time code recorded in the VTR 40 and the A/V server 41 arerespectively identical to the original video data, the original audiodata and the original time code recorded in the recording medium of theVTR 12 and the recording medium of the A/V server 13 of the transmissionsystem 1.

In the MPEG transmission system previously described in the Backgroundof the Invention section, the time code is not superposed for each frameon the encoded stream intended for transmission and, therefore, the timecode is transmitted for each frame to the receiving end together withthe encoded stream. However, in the digital data transmission systemshown in FIG. 1, the original time code attached to the originalmaterial data is superposed for each frame at the transmitting end and,therefore, the original time code attached to the original material datacan be reproduced at the receiving end. As a result, a recording mediummay be generated at the receiving end which has recorded thereinoriginal material data and the same time code associated with each frameof the material data as that recorded in a recording medium at thetransmitting end.

Thus, if the original time code recorded in the recording medium at thereceiving end is used, the same editing process as at the transmittingend may be performed at the receiving end. Also, since the recordingmedia at the transmitting end may be the same as those at the receivingend, the use of the editing list generated for the original materialdata at the transmitting end permits an editing process to be performedautomatically at the receiving end.

FIG. 2 illustrates a digital data processing system according to anotherembodiment of the present invention. The digital data transmissionsystem of FIG. 1 is different from the digital data processing system ofFIG. 2, in that, in the digital data transmission system of FIG. 1, thetransmitted encoded stream is decoded in the receiving system 3 andafter which the baseband video data and the baseband audio data areedited. On the other hand, in the digital data processing system of FIG.2, the baseband video data and the baseband audio data in decoded formare not edited and instead the encoded stream is edited.

The digital data processing system of FIG. 2 may include a basebandsystem 50A for processing and handling the baseband video data and thebaseband audio data and an encoding system SOB for handling the encodedstream.

The baseband system 50A in the digital data processing system of FIG. 2may include an A/V server 52 for reproducing the original material dataof the baseband from a randomly-accessible recording medium and aneditor 53 for generating an editing list EDL using the original materialdata recorded in the recording medium of the A/V server 52.

The encoding system SOB of the digital data processing system of FIG. 2,on the other hand, may include a video encoder 54 for encoding basebandvideo data DV reproduced from the A/V server 52 according to the MPEGstandard and outputting a video elementary stream; an audio encoder 55for encoding baseband audio data DA reproduced from the A/V server 52according to the MPEG standard and outputting an audio elementarystream; an AC3 encoder 56 for encoding baseband audio data DA reproducedfrom the A/V server 52 according to an AC3 standard and outputting anaudio elementary stream; a stream analyzer 57 for parsing and analyzingthe syntax of the elementary streams outputted from the video encoder54, the audio encoder 55 and the AC3 encoder 56 and extracting the timecode information described in the elementary streams; and a streamserver 59 for recording the elementary streams outputted from the videoencoder 54, the audio encoder 55 and the AC3 encoder 56 in arandomly-accessible recording medium.

The digital data processing system of FIG. 2 may further include a CPU51 for controlling and managing the devices or circuits of the basebandsystem 50A and the encoding system SOB. Such CPU 51 receives the timecode TC corresponding to each frame of the video data and the audio datareproduced from the A/V server 52, converts the received time code TCinto a predetermined format and supplies it to the video encoder 54, theaudio encoder 55 and the AC3 encoder 56.

The A/V server 52, like the A/V server 13 (FIG. 1), has recorded thereinthe baseband video data and the baseband audio data as original materialdata. Further, the video data and the audio data are recorded in therecording media as data associated with the original time code for eachframe. Also, the A/V server 52 has recorded therein two types of timecode, such as LTC and VITC, in a predetermined format. In the case wherethe original video data and the original audio data are reproduced fromthe A/V server 52, the original time code TC corresponding to each frameof the particular original video data and the particular original audiodata, respectively, may be outputted.

The editor 53 accesses the original video data and the original audiodata recorded in the A/V server 52, and sets editing points including anin-point and an out-point in the original video data and the originalaudio data. The editing operator operates the editor 53 so as to set anediting section defined by a plurality of in-points and out-points sothat the editing operator can select a desired scene or scenes in theoriginal video data and the original audio data. Then, an editing list(EDL) is generated in accordance with the set in-points and theout-points. The video data DV and the audio data DA outputted from theA/V server 52 are not edited by this editing list, but are thenew-edited original video data and the original audio data,respectively. However, according to an embodiment of this invention, theoriginal video data and the original audio data are actually edited inaccordance with the editing list generated by the editor 53, and theediting process for generating the edited video data and the editedaudio data is performed by the editor 58.

The video encoder 54 is a circuit for generating an encoded stream (alsocalled a video elementary stream) by compression-encoding the receivedoriginal video data DV according to the MPEG standard. Also, the videoencoder 54 receives the original time code TC corresponding to theoriginal video data DV for each frame from the CPU 51, and inserts orarranges the particular time code TC as a data element in the picturelayer of the encoded stream.

The audio encoder 55 is a circuit for generating an encoded audio stream(also called an audio elementary stream) by compression-encoding thereceived original audio data DA according to the MPEG standard. Also,the audio encoder 55 receives the original time code TC corresponding tothe original audio data DA for each frame from the CPU 51, and insertsor arranges the particular time code TC in the encoded stream.

The AC3 encoder 56, on the other hand, is a circuit for generating anencoded private stream (also called a private elementary stream) bycompression-encoding the received original audio data DA according tothe AC3 standard. Also, the AC3 encoder 56 receives the original timecode TC corresponding to the original audio data DA for each frame fromthe CPU 51, and inserts or arranges the particular time code TC in theencoded stream for each frame.

The location in the encoded stream at which the original time code isinserted will be described hereinafter.

The stream analyzer 57 parses and analyzes the syntax of the elementarystreams respectively supplied from the video encoder 54, the audioencoder 55 and the AC3 encoder 56. The stream analyzer 57 extracts thetime code information for each frame (or picture) described in the userdata area of the picture layer by parsing and analyzing the syntax ofthe elementary streams supplied thereto as described above. The streamanalyzer 57 supplies the editor 58 with the time code TC correspondingto each frame (picture) of the elementary streams supplied to the streamserver 59.

The editor 58 manages the recording and reproduction timing of thestream server 59 and the recording addresses of the data on therecording media. The editor 58 receives the time code TC extracted fromthe elementary stream by the stream(s) analyzer 58, generates a writeaddress corresponding to the time code TC, and supplies the writeaddress to the stream server 59. Specifically, the editor 58 may includea memory in the form of a table for relating an encoded stream recordedin the recording medium of the stream server 59 and the time codeattached to the frame thereof to each other. By utilizing this table,the address of the recording medium of the stream server 59 where theencoded stream corresponding to the desired time code is stored may bedetermined. Also, the editor 58 receives an editing list from the editor53 in the baseband system and controls the reproduction of the streamserver 59 based on the recording address in the memory previouslydescribed and the editing list. Specifically, the recording andreproduction of the stream server is controlled in such a manner as toreproduce the stream between the in-point and the out-point specified bythe editing list from the stream server 59. As a result, the editingstream outputted from the stream server 59 constitutes a streamcorresponding to the editing list generated in the editor 53.

As described above, in the digital data processing system of FIG. 2, anencoded stream may be edited as it is in accordance with the editinglist generated in the baseband system 50A.

The editing program containing the edited video data and the editedaudio data outputted from the A/V server 41 of the digital datatransmission system of FIG. 1 is baseband data. Therefore, this editingprogram, when transmitted to other transmission lines, may have to becoded again. However, in the digital data processing system of FIG. 2,the editing stream outputted from the stream server 59 has the state ofan encoded stream, and therefore can be transmitted to a transmissionmedium without additional encoding. As a result, the digital dataprocessing system of FIG. 2 may prevent the deterioration of the imagequality which otherwise might be caused by repetitive encodingprocessing.

FIG. 3 illustrates an example of a configuration of the video encoders16, 56. Each of the video encoders 16, 56 may include an encodercontroller 60 for controlling and managing all the devices or circuitsin the video encoder, an image rearranging circuit 61 for receiving thebaseband video data DV and rearranging the I picture (intra encodedpicture), the P picture (predictive encoded picture) and the B picture(bidirectionally predictive encoded picture) in the order of encoding, ascan conversion/macro blocking circuit 62 supplied with the outputteddata of the image rearranging circuit 61 for determining a framestructure or a field structure and performing a scan conversion andforming macro blocks of 16×16 pixels corresponding to the result of thedetermining, a motion detection circuit 63 for detecting and outputtingmotion vector data based on the output data of the scan conversion/macroblocking circuit 62, a subtraction circuit 64 for determining thedifference between the output data of the scan conversion/macro blockingcircuit 62 and the predictive image data, a DCT circuit 65 forperforming discrete cosine transformation (DCT) of the output data ofthe subtraction circuit 64 by block and outputting a DCT coefficient, aquantization circuit 66 for quantizing the output data of the DCTcircuit 65, a variable-length encoding circuit 67 for converting theoutput data of the quantization circuit 66 into a variable length code,and a buffer memory 68 for temporarily holding the output data of thevariable-length encoding circuit 67 and outputting it as a videoelementary stream (ES).

Each of the video encoders 16, 54 may further include an inversequantization circuit 69 for inversely quantizing the output data of thequantization circuit 66, an inverse DCT circuit 70 for performinginverse DCT of the output data of the inverse quantization circuit 69,an adder circuit 71 for adding the output data of the inverse DCTcircuit 70 and the predictive image data to each other and outputtingthe sum, a motion compensation circuit 72 for holding the output data ofthe adder circuit 71, compensating the motion based on the motion vectorand outputting the predictive image data to the subtraction circuit 64and the adder circuit 71, and a bit rate control unit 73 for controllinga target bit rate by controlling the quantization characteristic of thequantization circuit 66 based on the bit rate data generated from thevariable-length encoding circuit 67.

The image rearranging circuit 61 receives the baseband video data DV andrearranges the pictures in the order of encoding under the control ofthe encoder controller 60. The data with the pictures thereof rearrangedin a new order are supplied to the scan conversion/macro blockingcircuit 62. The scan conversion/macro blocking circuit 62 may performscan conversion processing and may form macro blocks from theframe/field data, based on the prediction mode of the data suppliedthereto. The motion detection circuit 63 detects the motion vector fromthe output data of the scan conversion/macro blocking circuit 62, andoutputs the motion vector data thus detected.

In the case where the supplied video data is encoded as an I picture,the output data of the scan conversion/macro blocking circuit 62 isdirectly inputted to the DCT circuit 65 for DCT operation, so that theDCT coefficient is quantized by the quantization circuit 66 and suppliedto the variable length encoding circuit 67, without taking thedifference with the predictive image data in the subtraction circuit 64.

In the case where the supplied video data is encoded as a P picture,predictive image data may be generated by the motion compensationcircuit 72 based on the image data corresponding to the past I or Ppicture held in the motion compensation circuit 72 and the motion vectorsupplied from the motion detection circuit 63, and the generatedpredictive image data are outputted to the subtraction circuit 64 andthe adder circuit 71. Also, the subtraction circuit 64 takes thedifference between the output data of the scan conversion/macro blockingcircuit 62 and the predictive image data supplied from the motioncompensation circuit 72. The difference is subjected to DCT processingby the DCT circuit 65 so as to obtain DCT coefficient data which isquantized by the quantization circuit 66. The quantized data aresupplied to the variable-length encoding circuit 67.

In the case where the supplied video data are encoded as a B picture,the predictive image data may be generated by the motion compensationcircuit 72 based on data of two images corresponding to the past andfuture I or P picture held in the motion compensation circuit 72 and twomotion vectors supplied from the motion detection circuit 63, and thegenerated predictive image data are outputted to the subtraction circuit64 and the adder circuit 71. Also, the subtraction circuit 64 takes thedifference between the output data of the scan conversion/macro blockingcircuit 62 and the predictive image data supplied from the motioncompensation circuit 72. The difference thereof is subjected to DCTprocessing by the DCT circuit 65 so as to obtain DCT coefficient datawhich is quantized by the quantization circuit 66. The quantized dataare supplied to the variable-length encoding circuit 67.

The encoder controller 60 may supply the variable-length encodingcircuit 67 with various encoding parameters defined in the MPEG standardsuch as the picture type, the prediction mode, the motion vector, thequantization step and the DCT mode, and may supply the variable-lengthencoding circuit 67 with the time code TC from the CPU 11 at the sametime. The encoding parameters are data elements which may be describedas or inserted in a sequence layer, a GOP layer, a picture layer, aslice layer, and a macroblock layer.

The variable-length encoding circuit 67 subjects the data quantized bythe quantization circuit 66 to variable-length encoding and, at the sametime, in accordance with the encoding data subjected to thevariable-length encoding and the various encoding parameters suppliedfrom the encoder controller 60, describes appropriate data and dataelements in the sequence layer, the GOP layer, the picture layer and themacroblock layer so as to generate an encoded stream. In generating thisencoded stream, the variable-length encoding circuit 67 describes orinserts the time code TC supplied from the encoder controller 60 in theuser data area of the picture layer so as to generate an encoded streamwith the time code information added (superposed) for each picture.

As described above, an encoded video elementary stream may be generatedhaving original time code information for each frame of the originalvideo data.

FIG. 4 illustrates an example of a configuration of the audio encoders17, 55 shown in FIGS. 1 and 2, respectively. Each of the audio encoders17, 55 may include a subband analysis filter bank 81 supplied with thebaseband audio data DA for splitting it into 32-band subband signals andoutputting the same, a linear quantizer 82 for quantizing each outputsignal of the subband analysis filter bank 81, and a bit stream formingunit 83 for generating encoded audio data based on each output signal ofthe linear quantizer 82, while at the same time adding an error checkfor CRC (cyclic redundancy check), the encoded side information to bedescribed hereinafter, the time code data TC from the CPU 11, and soforth to the encoded audio data so as to form a bit stream having apredetermined data structure and outputting it as an audio elementarystream (ES).

Each of the audio encoders 17, 55 may further include a FFT unit 84 forconducting Fast Fourier Transformation (FFT) of the audio data DAinputted thereto, a scale factor extraction unit 85 for extracting ascale factor from each output signal of the subband analysis filter bank81, a psychological auditory model forming unit 86 for forming apsychological auditory model for psychological auditory analysis usingan output signal of the FFT unit 84 and the scale factor extracted bythe scale factor extraction unit 85, a dynamic bit assigning unit 87 fordynamically assigning bits based on the psychological auditory modelformed by the psychological auditory model forming unit 86 and supplyingthe bit assignment information to the linear quantizer 82 so as tocontrol the quantization characteristic of the linear quantizer 82, anda side information encoding unit 88 for encoding the scale factorextracted by the scale factor extraction unit 85 and the bit assignmentinformation from the dynamic bit assigning unit 87 as side informationand supplying the encoded side information to the bit stream formingunit 83.

The subband analysis filter bank 81 receives the baseband audio data DA,splits the audio data DA into 32-band subband signals, and outputs thesubband signals to the linear quantizer 82. The FFT unit 84, on theother hand, receives the baseband audio data DA, subjects the audio dataDA to Fast Fourier Transformation and supplies the obtained signal tothe psychological auditory model forming unit 86.

The scale factor extraction section 85 extracts a scale factor from eachoutput signal of the subband analysis filter bank 81, and supplies theextracted scale factor information to the psychological auditory modelforming unit 86. The psychological auditory model forming unit 86 formsa psychological auditory model for psychological auditory analysis usingthe output signal of the FFT unit 84 and the scale factor informationextracted by the scale factor extraction unit 85.

The dynamic bit assigning unit 87 dynamically assigns bits based on thepsychological auditory model generated by the psychological auditorymodel forming unit 86, and generates a control signal for controllingthe quantization characteristic of the linear quantizer 82. Thequantization characteristic of the linear quantizer 82 is controlled bythe quantization characteristic control signal supplied from the dynamicbit assigning unit 87. The output signal of the linear quantizer 82 issupplied to the bit stream forming unit 83.

The side information encoding unit 88 codes the scale factor extractedby the scale factor extraction unit 85 and the bit assignmentinformation supplied from the dynamic bit assigning unit 87 as sideinformation, and supplies it to the bit stream forming unit 83.

The bit stream forming unit 83 generates encoded audio data using eachoutput signal of the linear quantizer 82 while at the same time addingan error check and the side information encoded by the side informationencoding unit 88 to the encoded audio data. Further, the bit streamforming unit 83 adds the time code data TC from the CPU 11, 51 to theencoded audio data and forms a bit stream having a predetermined datastructure. As a result, an audio elementary stream with a time codeadded thereto is generated.

FIG. 5 illustrates an example of a configuration of the AC3 encoders 18,56 shown in FIGS. 1 and 2, respectively. Each of the AC3 encoders 18, 56may include a frequency area conversion unit 91 for receiving thebaseband audio data DA, converting it into frequency area data andoutputting a frequency coefficient including an exponent part and amantissa. The exponent part of the frequency coefficient represents thespectral envelope of the audio data. Each of the AC3 encoders 18, 56 mayfurther include a spectral envelope encoding unit 92 for encoding theexponent part of the frequency coefficient outputted from the frequencyarea conversion unit 91, a quantization unit 93 for quantizing themantissa of the frequency coefficient outputted from the frequency areaconversion unit 91, a bit assigning unit 94 for assigning bits based onthe output data of the spectral envelope encoding unit 92 and supplyingthe bit assignment information to the quantization unit 93 so as tocontrol the quantization characteristic of the quantization unit 93, anda bit stream forming unit 95 for adding the time code data TC from theCPU 11, 51 to the output data of the spectral envelope encoding unit 92and the output data of the quantization unit 93 to form a bit streamhaving a predetermined data structure and outputting it as a privateelementary stream (ES).

The frequency area conversion unit 91 converts the baseband audio dataDA supplied thereto to the frequency area, processes the same so as toform a frequency coefficient having an exponent part and a mantissa,outputs the mantissa of the frequency coefficient to the quantizationunit 93, and outputs the exponent part of the frequency coefficient tothe spectral envelope encoding unit 92.

The spectral envelope encoding unit 92 encodes the exponent part of thefrequency coefficient supplied from the frequency area conversion unit91 and outputs the encoded data to the bit assigning unit 94 and the bitstream forming unit 95.

The quantization unit 93 quantizes the mantissa of the frequencycoefficient supplied from the frequency area conversion unit 91, andoutputs the quantized data to the bit stream forming unit 95.

The bit assigning unit 94 assigns bits based on the output encoded dataof the spectral envelope encoding unit 92, and outputs the bitassignment information to the quantization unit 93. The quantizationcharacteristic of the quantization unit 93 is controlled based on thebit assignment information from the bit assigning unit 94.

The bit stream forming unit 95 receives the time code data TC from theCPU 11, 51 and adds the particular time code data TC to the output dataof the spectral envelope encoding unit 92 and the output data of thequantization unit 93.

As a result of the above-described processing, a bit stream having apredetermined data structure may be formed and outputted as a privateelementary stream (ES). Such private elementary stream has the time codeadded thereto.

A structure of a stream encoded according to the MPEG standard with timecode data added thereto will now be described.

FIG. 6 is a diagram of the syntax of a video stream based on MPEG. Thevideo encoders 16, 54 may generate an encoded stream according to suchsyntax. Additionally, the video decoder 36 (FIG. 1) may extract aplurality of significant data items (data elements) from the encoded bitstream by analyzing the encoded stream in accordance with the syntax ofFIG. 6. In the syntax of FIG. 6 which will be described hereinbelow,functions and conditional statements are expressed in thin letters, anddata elements are expressed in thick letters. The data elements aredescribed by Mnemonics indicating the name, the bit length and bit typeand the order of transfer thereof.

Initially, the functions used in the syntax of FIG. 6 will be explained.The syntax of FIG. 6 may be used for extracting predeterminedsignificant data from the transmitted encoded stream at the videodecoder. The syntax used by the video encoder is the one in whichconditional statements such as “if” and “while” statements are omittedfrom the syntax of FIG. 6.

The next_start_code( ) function described first in video_sequence( ) isa function for searching for the start code described in the bit stream.The encoded stream generated in accordance with the syntax of FIG. 6 hasdescribed therein the data elements defined by the sequence_header( )function and the sequence_extension( ) function. This sequence_header( )function is for defining the header data of the sequence layer of theMPEG bit stream, and the sequence_extension( ) function is for definingthe extension data of the sequence layer of the MPEG bit stream.

The “do { } while” syntax arranged next to the sequence_extension( )function is a syntax indicating that the data elements described basedon the function in { } of the “do” statement are described in theencoded data stream during the time when the condition defined by the“while” statement is true. The nextbits( ) function used for this“while” statement is for comparing the bit or bit string described inthe bit stream with the data elements referred to. In the case of thesyntax of FIG. 6, the nextbits( ) function is used for comparing the bitstring 20 in the bit stream with the sequence_end_code indicating theend of the video sequence, and when the bit string in the bit streamfails to coincide with the sequence_end_code, the condition of the“while” statement becomes true. Consequently, the “do { } while” syntaxarranged next to the sequence_extension( ) function indicates that thedata elements defined by the function in the “do” statement aredescribed in the encoded bit stream during the period when thesequence_end_code indicating the end of the video sequence fails toappear in the bit stream.

In the encoded bit stream, the data elements defined by theextension_and_user_data(0) function are described next to each dataelement defined by the sequence_extension( ) function. Thisextension_and_user_data(0) function is for defining the extension dataand the user data in the sequence layer of the MPEG bit stream.

The “do { } while” syntax arranged next to theextension_and_user_data(0) function is a function indicating that thedata elements described based on the function in { } of the “do”statement is described in the bit stream during the period when thecondition defined by the “while” statement is true. The nextbits( )function used in this “while” statement is a function for judgingwhether the bit or bit string appearing in the bit stream coincides withthe picture_start_code or the group_start_code, and in the case wherethe bit or the bit string appearing in the bit stream coincides with thepicture_start_code or the group_start_code, the condition defined by the“while” statement is true. As a result, the “do { } while” syntaxindicates that in the case where the picture_start_code or thegroup_start_code appears in the encoded bit stream, the code of the dataelements defined by the function in the “do” statement is described nextto the start code.

The “if” statement described first in the “do” statement indicates thecondition where the group_start_code appears in the encoded bit stream.In the case where the condition of this “if” statement is true, the dataelements defined by the group_of_picture_header( ) function and theextension_and_user_data(1) function are sequentially described next tothe group_start_code in the encoded bit stream.

The above-mentioned group_of_picture_header( ) function is a functionfor defining the header data of the GOP layer of the MPEG encoded bitstream, and the extension_and_user_data(1) function is for defining theextension data and the user data of the GOP layer of the MPEG encodedbit stream.

Further, in this encoded bit stream, the data elements defined by thepicture_header( ) function and the picture_coding_extension( ) functionare described next to the data elements defined by thegroup_of_picture_header( ) function and the extension_and_user_data(1)function. Of course, in the case where the condition of the “if”statement explained above is not true, the data elements defined by thegroup_of_picture_header( ) function and the extension_and_user_data(1)function are not described. Therefore, the data elements defined by thepicture_header( ) function, the picture_coding_extension( ) function andthe extension_and_user_data(2) function are described next to the dataelements defined by the extension_and_user_data(0) function.

The picture_header( ) function is a function for defining the headerdata of the picture layer of the MPEG encoded bit stream, and thepicture_coding_extension( ) function is a function for defining thefirst extension data of the picture layer of the MPEG encoded bitstream.

The extension_and_user_data(2) function is a function for defining theextension data and the user data of the picture layer of the MPEG codedbit stream. The user data defined by the extension_and_user_data(2)function may be described or inserted in the picture layer for eachpicture. In accordance with the present invention, the time codeinformation is described or arranged as the user data defined by thisextension_and_user_data(2) function.

In the encoded bit stream, the data elements defined by thepicture_data( ) function are described next to the user data of thepicture layer. This picture_data( ) function is a function fordescribing the data elements for the slice layer and the macroblocklayer.

The “while” statement described next to the picture_data( ) function isa function for determining the condition of the next “if” statementwhile the condition defined by this “while” statement is true. Thenextbits( ) function used in this “while” statement is a function fordetermining whether the picture_start_code or the group_start_code isdescribed or not in the encoded bit stream, and in the case where thepicture_start_code or the group_start_code is described in the bitstream, the condition defined by this “while” statement becomes true.

The next “if” statement is a conditional statement for determiningwhether or not the sequence_end_code is described in the encoded bitstream, and in the case where the sequence_end_code is not so described,indicates that the data elements defined by the sequence_header( )function and the sequence_extension( ) function are described. Thesequence_end_code is a code indicating the end of a sequence of theencoded bit stream. Until the encoded stream ends, the data elementsdefined by the sequence_header( ) function and the sequence_extension( )function are described in the encoded stream.

The data elements described by the sequence_header( ) function and thesequence_extension( ) function are the same as the data elementsdescribed by the sequence_header( ) function and the sequence_extension( ) function described at the head of the sequence of the video stream.In this way, the same data are described in the stream to prevent thesituation in which in the case where the bit stream receiver starts thereceiving operation midway of the data stream (for example, the bitstream portion corresponding to the picture layer), data of the sequencelayer cannot be received and the stream cannot be decoded.

The 32-bit sequence_end_code indicating the end of the sequence isdescribed next to the data elements defined by the last sequence_header() function and the sequence_extension( ) function, that is, at the endof the data stream.

The sequence_header( ) function, the sequence_extension( ) function, theextension_and_user_data(0) function, the group_of_pictures_header( )function and the extension_and_user_data(1) function will now be furtherexplained.

The data elements defined by the sequence_header( ) function may includea sequence_header_code, sequence_header_present_flag,horizontal_size_value, vertical_size_value, aspect_ratio_information,frame_rate_code, bit_rate_value, marker_bit, VBV_buffer_size_value,constrained_parameter_flag, load_intra_quantizer_matrix,intra_quantizer_matrix, load_non_intra_quantizer_matrix andnon_intra_quantizer_matrix.

The sequence_header_code is data indicating the start sync code of thesequence layer. The sequence_header_present_flag is data indicatingwhether the data in the sequence_header is valid or not. Thehorizontal_size_value is data which may include the low-order 12 bits ofthe number of pixels in the horizontal direction of the picture. Thevertical_size_value is data which may include the low-order 12 bits ofthe number of vertical lines of the picture. Theaspect_ratio_information is data indicating the aspect ratio (the ratiobetween longitudinal and lateral lengths) of the pixels or the displayscreen. The frame_rate_code is data indicating the picture displayperiod. The bit_rate_value is data of the low-order 18 bits (rounded toeach 400 bsp) of the gbit rate for limiting the amount of bitsgenerated. The marker_bit is bit data inserted for preventing start codeemulation (that is, the false detection of a start code). TheVBV_buffer_size_value is the low-order 10 bit data of the value fordetermining the size of a virtual buffer (video buffer verifier) forcontrolling the amount of code generated. The constrained_parameter_flagis data indicating that each parameter is within the constraint. Theload_intra_quantizer_matrix is data indicating the presence of thequantization matrix data for intra MB. The intra_quantizer_matrix isdata indicating the value of the quantization matrix for intra MB. Theload_non_intra_quantizer_matrix is data indicating the presence of thequantization matrix data for non-intra MB. Thenon_intra_quantizer_matrix is data indicating the value of thequantization matrix for non-intra MB.

The data elements defined by the sequence_extension( ) function mayinclude an extension_start_code, extension_start_code_identifier,sequence_extension_present_flag, profile_and_level_indication,progressive_sequence, chroma_format, horizontal_size_extension,vertical_size_extension, bit_rate_extension, vbv_buffer_size_extension,low_delay, frame_rate_extension_n and frame_rate_extension_d and soforth.

The extension_start_code is data indicating the start sync code of theextension data. The extension_start_code_identifier is data indicatingwhich extension data is sent. The sequence_extension_present_flag isdata indicating whether the data in the sequence extension is valid ornot. The profile_and_level_indication is data for specifying the profileand level of the video data. The progressive_sequence is data forindicating that the video data are sequentially scanned. Thechroma_format is data for specifying the color difference format of thevideo data. The horizontal_size_extension is the high-order 2-bit dataadded to the horizontal_size_value of the sequence header. Thevertical_size_extension is the high-order 2-bit data added to thevertical_size_value of the sequence header. The bit_rate_extension isthe high-order 12-bit data added to the bit_rate_value of the sequenceheader. The vbv_buffer_size_extension is the high-order 8-bit data addedto the vbv_buffer_size_value of the sequence header. The low_delay isdata indicating that no B picture is included. Theframe_rate_extension_n is data for obtaining the frame rate incombination with the frame_rate_code of the sequence header. Theframe_rate_extension_d is the data for obtaining the frame rate incombination with the frame_rate_code of the sequence header.

The extension_and_user_data(i) function does not describe the dataelements defined by the extension_data ( ) function but only the dataelements defined by the user_data( ) function if (i) is other than 2. Asa result, the extension_and_user_data(0) function describes only thedata elements defined by the user_data( ) function.

The data elements defined by the group_of_pictures_header( ) functioninclude the group_start_code, group_of_picture_header_present_flag,time_code, closed_gop and broken_link.

The group_start_code is data indicating the start sync code of the GOPlayer. The group_of_picture_header_present_flag is data indicatingwhether the data elements in the group_of pictures_header are valid ornot. The time_code indicates the time from the head of the sequence ofthe leading picture of the GOP. The closed_gop is flag data indicatingthat the picture in the GOP is reproducible independently of other GOPs.The broken_link is flag data indicating that the B picture at the headin the GOP cannot be reproduced correctly for editing or the like.

The extension_and_user_data(1) function, like theextension_and_user_data(0) function, is for describing only the dataelements defined by the user_data( ) function.

The picture_header( ) function, the picture_coding_extension( )function, the extensions_and_user_data(2) and the picture_data( ) fordescribing the data elements for the picture layer of the encoded streamwill now be further described.

The data elements defined by the picture_header( ) function includepicture_start_code, temporal_reference, picture_coding_type, vbv_delay,full_pel_forward_vector, forward_f_code, full_pel_backward_vector,backward_f_code, extra_bit_picture and extra_information_picture.

The picture_start_code is data indicating the start sync code of thepicture layer. The temporal_reference is the number indicating the orderof picture display and the data reset at the head of the GOP. Thepicture_coding_type is data indicating the picture type. The vbv_delayis data indicating the initial state of the virtual buffer at the timeof random access. The full_pel_forward_vector is data indicating whetherthe accuracy of the forward motion vector is in units of an integer or ahalf pixel. The forward_f_code is data indicating the motion vectorsearch area in a forward direction. The full_pel_backward_vector is dataindicating whether the accuracy of the reverse motion vector is in unitsof an integer or a half pixel. The backward_f_code is data indicatingthe motion vector search area in a reverse direction. Theextra_bit_picture is a flag indicating the presence of the succeedingadditional information. For example, when this extra_bit_picture is “1”,it indicates it is followed by the extra_information_picture, and whenthe extra_bit_picture is “0”, it indicates the absence of the succeedingdata. The extra_information_picture is reserved information according tothe standard.

The data elements defined by the picture_coding_extension( ) functionmay include an extension_start_code, extension_start_code_identifier,f_code[0][0], f_code[0][1], f_code[1][0], f_code[1][1],intra_dc_precision, picture_structure, top_field_first,frame_predictive_frame_dct, concealment_motion_vectors, q_scale_type,intra_vlc_format, alternate_scan, repeat_first_field,chroma_(—)420_type, progressive_frame, composite_display_flag, v_axis,field_sequence, sub_carrier, burst_amplitude and sub_carrier_phase.

The extension_start_code is a start code indicating the start of theextension data of the picture layer. The extension_start_code_identifieris the code indicating which extension data is sent. The f_code[0][0] isdata indicating the horizontal motion vector search area in a forwarddirection. The f_code[0][1] is data indicating the vertical motionvector search area in a forward direction. The f_code[1][0] is dataindicating the horizontal motion vector search area in a backwarddirection. The f_code[1][1] is data indicating the vertical motionvector search area in a backward direction. The intra_dc_precision isdata indicating the accuracy of the DC coefficient. Thepicture_structure is data indicating a frame structure or a fieldstructure. In the case of field structure, it also indicates whether ahigh-order field or a low-order field is involved. The top_field_firstis data indicating whether the first field is high or low in the case ofthe frame structure. The frame_predictive_frame_dct is data indicatingthat the prediction of the frame mode DCT is limited to the frame modein the case of the frame structure. The concealment_motion_vectors isdata indicating that the intra macroblock is accompanied by a motionvector for hiding a transmission error. The q_scale_type is dataindicating which of a linear quantization scale or a nonlinearquantization scale is used. The intra_vlc_format is data indicatingwhether another two-dimensional VLC is used for the intra macroblock.The alternate_scan is data indicating which of a zig-zag scan or analternate scan was selected or used. The repeat_first_field is the dataused for the 2:3 pull-down. The chroma_(—)420_type is data indicatingthat it has the same value as the progressive_frame when the signalformat is 4:2:0, and it is zero otherwise. The progressive_frame is dataindicating whether this picture has been successfully scannedsequentially or not. The composite_display_flag is data indicatingwhether the source signal has been a composite signal or not. The v_axisis a data used only when source bitstream represents a signal that hadpreviously been encoded according to PAL system. The field_sequence is adata defining the number of the field in the eight field sequence usedin PAL systems or the four field sequence used in NTSC systems. Thesub_carrier is a data indicating relationship between sub_carrier andline frequency. The burst_amplitude is a data defining the burstamplitude for PAL or NTSC. The sub_carrier_phone is a data defining thephase of reference sub_carrier at the field-synchronization data.

The extension_and_user_data(2) function, as shown in FIG. 7, describesthe data elements defined by the extension_data( ) function in the casewhere the extension_start_code exists in the encoded bit stream. In theabsence of the extension_start_code in the bit stream, however, the dataelements defined by the extension_data( ) are not described in the bitstream. In the case where the user_data_start_code exists in the bitstream, the data elements defined by the user_data( ) function aredescribed next to the data elements defined by the extension_data( )function.

The user_data( ) function, as shown in FIG. 8, is a function fordescribing the data elements such as the user_data_start_code, thetime_code( ) function and the user_data.

The user_data_start_code is a start code for indicating the start of theuser data area of the picture layer of the MPEG bit stream. The “while”syntax described next to the user_data_start_code is true as long as24-bit data including 23 0s and the succeeding 1 does not appear in theencoded bit stream. That is, such 24-bit data including the 23 0sfollowed by 1 may be attached to the head of all the start codes and, asa result, the positions of all the start codes can be found in theencoded bit stream by having the start code(s) arranged behind such 24bits.

The time_code( ) function is a function for describing the time code.Specifically, as shown in FIG. 9, data elements described by thetime_code( ) function may include a time_code_start_code indicating thestart code for recognizing the position where the time code is describedin the user data area of the picture layer, a data_ID indicating theidentification code of the data following the start code, and time codedata corresponding to the data identification code.

In the time_code( ) function of the present invention, as shown in FIGS.11A and 11B, if the data identification code data_ID is an ID codeindicating the VITC, the 72-bit VITC is described next to it. Also, inthe case where the data identification code data_ID is the ID codeindicating the LTC, the 72-bit LTC is described next to it. The dataelements described by the time_code( ) function will be furtherdescribed hereinafter.

The data elements defined by the picture_data ( ) function are thosedefined by the slice( ) function. In the case where a slice_start_codeindicating the start code of the slice( ) function is absent in the bitstream, however, the data elements defined by this slice( ) function arenot described in the bit stream.

The slice( ) function is for describing the data elements for the slicelayer and, specifically, for describing data elements such asslice_start_code, slice_quantiser_scale_code, intra_slice_flag,intra_slice, reserved_bits, extra_bit_slice, extra_information_slice andextra_bit_slice and the data elements defined by the macroblock( )function.

The slice_start_code is a start code indicating the start of the dataelements defined by the slice( ) function. Theslice_quantiser_scale_code is data indicating the quantization step sizeset for the macroblock existing in the slice layer. In the case wherethe quantiser_scale_code is set for each macroblock, however, the dataof macroblock_quantiser_scale_code set for each macroblock may be usedin a priority manner. The intra_slice_flag is a flag indicating whetherthe intra_slice and reserved_bits are present in the bit stream. Theintra_slice is data indicating whether the non-intra macroblock ispresent in the slice layer or not. In the case where any one of themacroblocks in the slice layer is a non-intra macroblock, theintra_slice is “0”, while in the case where all the macroblocks in theslice layer are non-intra macroblocks, the intra_slice is “1”. Thereserved_bits are 7-bit data and assumes the value “0”. Theextra_bit_slice is a flag indicating that additional information existsin the encoded stream and, when the extra_information_slice is present,it is set to “1”. In the absence of the additional information, it isset to “0”.

The macroblock( ) function is for describing the data elements for themacroblock layer and, specifically, is for describing data elements suchas a macroblock_escape, macroblock_address_increment andmacroblock_quantiser_scale_code, and the data elements defined by themacroblock_modes( ) function and the macroblock_vectors(s) function.

The macroblock_escape is a fixed bit string indicating whether thehorizontal difference between a reference macroblock and the precedingmacroblock is not less than 34 or not. In the case such horizontaldifference is not less than 34, 33 is added to the value of themacroblock_address_increment. The macroblock_address_increment is dataindicating the difference in the horizontal direction between thereference macroblock and the preceding macroblock. If there exists amacroblock_escape before the macroblock_address_increment, the sum of 33and the value of the macroblock_address_increment is the data indicatingthe horizontal difference between an actual reference macroblock and thepreceding macroblock. The macroblock_quantiser_scale_code is thequantization step size set for each macroblock. Theslice_quantizer_scale_code indicates the quantization step size of theslice layer and is set in each slice layer. In the case where themacroblock_quantiser_scale_code is set for the reference macroblock,however, this quantization step size is selected.

The structure of the stream generated by the syntax explained withreference to FIGS. 6 to 9 will now be further explained with referenceto FIG. 10.

FIG. 10 illustrates data structure of a MPEG encoded stream. As shown inFIG. 10, the data structure of a video elementary stream may include atleast the sequence layer, the GOP layer and the picture layer.

The sequence layer may have the data elements defined by thenext_start_code( ) function 101, the sequence_header( ) function 102,the extention_start_code 103, the sequence_extention( ) function 104 andthe extention_and_user_data(0) function 105. The GOP layer may have thedata elements defined by the group_start_code 106, thegroup_of_pictures_header( ) function 107 and theextention_and_user_data(1) function 108. The picture layer may have thedata elements defined by the picture_header( ) function 109, thepicture_coding_extention( ) function 110, the extention_and_user_data(2)function 111 and the picture_data function 112. The sequence_end_code113 is described at the end of the video sequence.

The extention_and_user_data(2) function 111 contains the data elementsdefined by the user_data_start_code 114, the user_data( ) function 115and the next_start_code 116. With regard thereto, reference is made tothe syntax explained above with reference to FIG. 7.

The user_data( ) function 115 contains the data elements defined by thetime_code( ) function 117 and the user_data 118. With regard thereto,reference is made to the syntax explained above with reference to FIG.8.

The data elements described by the time_code ( ) function will now befurther explained with reference to FIGS. 11A and 11B.

FIG. 11A illustrates an example of the VITC, the LTC and the ancillarydata in the user area of the picture layer. FIG. 11B illustrates thedata structure of the 72-bit VITC or LTC.

As shown in FIG. 11A, the ID code data_ID of the data recorded in theuser data area is described next to the 32-bit time_code_start_code.This ID code data_ID may be preset or configured in accordance with thevalues shown in FIG. 12. If the data_ID indicates “03”, for example, theVITC is described in the next 72 bits. In the case where the data_IDindicates “04”, on the other hand, the LTC is described in the next 72bits.

In FIG. 11B, the “CF” in the first bit indicates a color frame, and the“DF” in the second bit represents a drop frame. The six bits from thethird to the eighth bit indicate the “frame” portion of the time code,the ninth bit indicates the phase correction, and the 7 bits from the10th to the 16th bit indicate the “seconds” portion of the time code.The character “1” in the 17th, 34th, 51st and 68th bits is a marker bitto prevent a successive appearance of 23 zeros. By inserting a markerbit at predetermined intervals in this way, start code emulation can beprevented.

The characters “BG” of the 18th bit, 26th bit and 27th bit indicate abinary group. The seven bits from the 19th to the 25th bit indicate the“minutes” portion in the time code, and the six bits from the 28th tothe 33rd bit indicates the “hour” portion of the time code.

The 16 bits from the 35th to the 50th bit and the 16 bits from the 52ndto the 67th bit are reserved for permitting the user to describe adesired user data. The last four bits are stuffing bits for aligning thebyte or bytes.

An explanation of a method of adding a time code to the encoded streambased on the MPEG standard will now be provided.

In a video elementary stream, the pictures are rearranged for theconvenience of encoding. Two methods may be utilizing for adding thetime code to the video elementary stream. In the description thatfollows, the period (M) at which the I picture or P picture appears isassumed to be 3.

FIG. 13 refers to a first method of adding the time code to the videoelementary stream. In FIG. 13, (a) indicates the picture type in theinput video data of the video encoder 16. Characters I, P, and Bdesignate the I picture, the P picture and the B picture, respectively.The attached numerical characters designate the order of the pictures ofeach picture type. FIG. 13(b), shows, in simplified fashion, the timecode attached to each picture. According to the first method, the timecode is added to the video elementary stream without taking therearrangement of the picture into account, and the time code is attachedagain at the time of reproduction. More specifically, and with referenceto FIG. 1, once the CPU 11 has acquired a time code, the time code isrecorded directly taking into consideration the time delay before it isrecorded in the user data 115 (FIG. 10). The picture type and the timecode added at the time of input to the video decoder 36 according tothis first method are shown in FIGS. 13(c) and (d). When the time codeis added by the first method, the video decoder 36 attaches the timecode, which may be inputted with the I or P picture to the first next Bpicture, and the time code which may be inputted with the particular Bpicture to the second next B picture. Also, the time code inputted withthe second B picture is attached to the I or P picture. FIGS. 13(e) and13(f) show the picture types and the time codes of the output video dataof the video decoder 23 in such a case.

FIG. 14 refers to a second method of adding a time code to a videoelementary stream. In FIG. 14, (a) designates the picture types in theinput video data of the video encoder 16, and (b) designates the timecodes, in simplified fashion, inputted with each picture. According tothe second method, the time code is added to the video elementary streamtaking the picture rearrangement into account, and the time code is notattached again at the time of reproduction. When the CPU 11 (FIG. 1) hasacquired the time code, the CPU rearranges and records it whilerearranging the picture to assure the same correspondence between thepicture and the time code before and after the picture rearrangement inview of the delay before the time code is recorded in the user data 115(FIG. 10). FIGS. 14(c) and 14(d) illustrate the picture types and thetime codes inputted to the video decoder 23 in which the time code isadded according to the second method. In the case where the time code isadded according to the second method, the video decoder 36 rearrangesthe time code like the picture to assure correspondence between eachpicture and the time code. The picture types and the time codes of theoutput video data of the video decoder 36 for this case are shown inFIGS. 14(e) and 14(f).

A method of adding a time code to the audio elementary stream will nowbe described.

FIG. 15 is representative of the data structure of the audio elementarystream according to the MPEG audio standard. As shown in FIG. 15, anaudio elementary stream may include a number of data elements such as,from the head thereof, a header (header) 121, an error check(error_check) 122, audio data (audio_data) 123, and an ancillary data(ancillary_data)124.

The ancillary data 124 may represent an area which corresponds to eachframe (audio frame) as a unit of decoding and reproduction and in whicharbitrary data can be recorded in the data structure of the audio streamshown in FIG. 15.

The audio encoded stream, unlike the video stream, may have a size foreach frame fixed by the bit rate. The amount of data for each frame maybe 384×bit rate÷sampling frequency. The data amount in the area of theancillary data 124 may be equal to the data amount of one frame less thedata amount actually used in each area of the header 121, the errorcheck 122 and the audio data 123.

According to this embodiment, the time code is recorded in the area ofthe ancillary data 124 of the audio elementary stream shown in FIG. 15.The method of describing or inserting the time code in the ancillarydata 124 is the same as that for describing or inserting the time codein the user data area explained with reference to FIGS. 11A and 11B. A16-bit audio_phase (audio phase information) may be described, inaddition to the time code such as VITC or LTC, in the area of theancillary data 124 of the audio encoded stream. In the case where thetime_code_start_code in the ancillary data 124 is followed by thedata_ID as an ID code indicating the audio phase information, then, theaudio_phase is described in the next two bytes. This audio phaseinformation is data for indicating the phase difference between theaudio frame and the video frame since the audio frame may not besynchronized with the frame in the video stream (hereinafter referred toas the “video frame”).

The phase difference between the video frame and the audio frame willnow be explained with reference to FIGS. 16A and 16B. FIG. 16A showsvideo frames in which each block represents one video frame. Thenumerals in the figure show the time codes corresponding to therespective video frames. FIG. 16B, on the other hand, shows the audioframes in which each block represents one audio frame and in which thenumerals designate the time codes recorded which correspond to therespective video frames. As seen from FIGS. 16A and 16B, the audioframes are not synchronized with the video frames. According to thisembodiment, the time lag between the time code recorded in each audioframe and the actual starting point of the audio frame is regarded as aphase difference (designated by characters A to F in FIG. 16B), and thephase difference for each audio frame is described as audio phaseinformation, together with the time code, in the encoded stream. Thisaudio phase information may be expressed as the number of samples of theaudio data.

A method of adding the time code to the AC3 stream constituting aprivate elementary stream will now be explained. FIG. 17 indicates thedata structure of the AC3 stream according to the AC3 standard. As shownin FIG. 17, the data structure of the AC3 stream has areas of, from thehead thereof, sync information (syncinfo) 131, bit stream information(BSI) 132, an audio block (audblk) 133, auxiliary data (auxdata) 134 andan error check (error-check) 135 in that order.

The area of the auxiliary data 134 may exist for each frame (sync frame)as a unit of decoding and reproduction and may be where arbitrary datacan be recorded in the data structure of the AC3 stream. The amount ofdata in the area of the auxiliary data 134 may be equal to the dataamount left after the data amount used in the areas other than that ofthe auxiliary data 134 is taken from the data amount of one frame.

According to this embodiment, the time code (including the user bits) isrecorded in the area of the auxiliary data 134 of the data structure ofthe AC3 stream shown in FIG. 17. The method of describing or insertingthe time code in the auxiliary data 134 may be the same as that fordescribing or inserting the time code in the ancillary data 124 of theaudio encoded stream.

As explained above, according to the present invention, time codeinformation may be recorded in an area which can exist for each unit ofdecoding and reproduction and in which arbitrary data can be recorded inthe data structure of the stream. Specifically, the time code for avideo elementary stream may be recorded in the area of the user data 115(FIG. 10), the time code for an audio elementary stream may be recordedin the area of the ancillary data 124 (FIG. 15), and the time code foran AC3 stream may be recorded in the area of the auxiliary data 134(FIG. 17). As a result, according to the present invention, the timecode attached to the material data can be accurately transmitted as asignal corresponding to the stream for each unit of decoding andreproduction.

Also, according to the present invention, time code information may beattached to each of a video stream, an audio stream and an AC3 stream.As a result, even in the case where the streams are separated as in thereceiving system 3 (FIG. 1), no stream lacks the time code information.This is very advantageous because the time information is not lost evenin the case where each stream is stored, for example, in a hard disk andreused.

Further, according to the present invention, the time code including theuser bits can be recorded in each of the video stream, the audio streamand the AC3 stream. Therefore, arbitrary information recorded as theuser bits can also be transmitted accurately as a signal correspondingto each stream.

According to the present invention, which is not limited to theaforementioned embodiments, the format in which the time codeinformation is attached to the video elementary stream, the audioelementary stream and the private elementary stream (AC3 stream) is notlimited to that shown in the embodiments but other appropriate formatsmay also be utilized.

As described above, in an encoded stream generating device or methodaccording to this invention, the time code attached to the material datamay be recorded in an area which can exist for each unit of decoding andreproduction and in which arbitrary data can be recorded in the datastructure of the encoded stream. Therefore, the time code attached tothe material data can be accurately transmitted as a signalcorresponding to the encoded stream for each unit of decoding.

In an encoded stream generating device or method according to anotheraspect of this invention, an encoded stream may be generated in whichthe time code attached to each frame of the source video data isdescribed in the picture layer of a plurality of layers constituting theencoded stream. As a result, an encoded stream can be generated in whichthe time code attached to the original material data is described orinserted for each picture.

In an encoded stream generating device or method according to stillanother aspect of this invention, an encoded stream may be generated inwhich data elements indicating the time code attached to the sourcevideo data are described or inserted in the user data area of thepicture area of the encoded stream, thereby leading to the advantagethat an encoded stream can be generated in which the time code attachedto the original material data is described or inserted in a mannercorresponding to each picture.

In a data transmission system or method according to this invention, anencoded stream may be generated in which the time code attached to eachframe of the source video data is described or inserted in the picturelayer of a plurality of layers at the transmitting end, and this encodedstream is transmitted. At the receiving end, the encoded stream isdecoded, and by analyzing the syntax of the encoded stream, the timecode is extracted from the picture layer of the encoded stream, and thedecoded data and the extracted time code information which are relatedto each other may be stored in a recording medium. In this way, arecording medium may be obtained which has the same data as that of thedata source. As a result, an encoded stream can be generated andtransmitted in which the time code attached to the original materialdata is described in a manner corresponding to each picture. Also, atthe receiving end, a recording medium may be obtained having theoriginal material data and the time code attached to each frame of theoriginal material data recorded thereon.

In an editing system or method according to this invention, an editinglist may be generated based on editing points set in the source videodata, and an encoded stream may be generated in which the time codeattached to each frame of the source video data is described or insertedin the picture layer of a plurality of layers at the transmitting end.This encoded stream may be transmitted to the receiving end at which theencoded stream is decoded, and by analyzing the syntax of the encodedstream, the time code is extracted from the picture layer of the encodedstream, and the decoded source video data is edited based on the timecode and the editing list. As a result, the same editing process as atthe transmitting end can be performed at the receiving end using thetime code attached to each frame of the source video data.

In an editing system or method according to another aspect of thisinvention, an editing list may be generated based on editing points setin the source video data, and an encoded stream may be generated inwhich the time code attached to each frame of the source video data isdescribed or inserted in the picture layer of a plurality of layers.This encoded stream may be edited based on the time code and the editinglist obtained by analyzing the syntax of the encoded stream. As aresult, the encoded stream can be edited using the time code attached toeach frame of the source video data.

In an editing system or method according to still another aspect of thisinvention, an editing list may be generated based on editing points setby processing baseband source video data, and an encoded stream may begenerated in which the time code attached to each frame of the sourcevideo data is described or inserted in the picture layer of a pluralityof layers of the encoded stream having a hierarchical structure, whichlayers are generated by encoding the source video data. The encodedstream may be edited at a stream level based on the time code and theediting list obtained by analyzing the syntax of the encoded stream. Asa result, the encoded stream can be edited at a stream level and thedeterioration of the image quality can be prevented.

Although preferred embodiments of the present invention andmodifications thereof have been described in detail herein, it is to beunderstood that this invention is not limited to these embodiments andmodifications, and that other modifications and variations may beeffected by one skilled in the art without departing from the spirit andscope of the invention as defined by the appended claims.

What is claimed is:
 1. A data transmission system comprising: datasupply means operable with a first recording medium for storing sourceaudio data, source video data and time code information attached to thesource video data, wherein the time code information is associated witheach video frame of said source video data; encoding means forgenerating an encoded stream having a first audio stream encoded inaccordance with a moving pictures expert group (MPEG) standard, a secondaudio stream encoded in accordance with a standard different from theMPEG standard, and a plurality of layers generated by encoding thesource video data, and for describing the time code information attachedto each frame of the source video data into a picture layer among saidplurality of layers; transmission means for transmitting the encodedstream; decoding means for decoding the encoded stream transmittedthrough the transmission means and extracting the time code informationfrom the picture layer of the encoded stream by parsing the syntax ofthe encoded stream; and data recording means for recording the datadecoded by the decoding means and the time code information extracted bythe decoding means in a manner associated with each other onto a secondrecording medium so as to obtain the same data as on the first recordingmedium.
 2. A data transmission system according to claim 1, wherein theplurality of layers of the encoded stream include a sequence layer, aGOP layer, the picture layer, a slice layer, and a macroblock layer. 3.A data transmission system according to claim 2, wherein: a data elementdefined by a sequence_header ( ) function, a data element defined by asequence_extention( ) function and a data element defined by anextention_and_user_data(0) are described in the sequence layer; a dataelement defined by a group_of_picture_header( ) function and a dataelement defined by an extention_and_user_data(1) are described in theGOP layer; a data element defined by a picture_header( ) function, adata element defined by a picture_coding_extention( ) function and adata element defined by an extention_and_user_data(2) are described inthe picture layer; and the time code information is defined by atime_code( ) function indicated by a user_data( ) function indicated byan extention_and_user_data(2) function.
 4. A data transmission systemaccording to claim 1, wherein the time code information is datadescribed in the user data area of the picture layer and a marker bit isinserted therein at predetermined intervals so that the time codeinformation may not be mistaken for a unique start code contained in theencoded stream when analyzing the encoded stream.
 5. A data transmissionsystem according to claim 1, wherein time code information associatedwith each frame of the source audio data is attached to the source audiodata and wherein the time code information attached to each frame of thesource audio data is described in the auxiliary data areas of theencoded first and second audio streams.
 6. A data transmission systemaccording to claim 5, wherein phase information indicating a phasedifference between a respective frame of the source video data and thecorresponding frame of the audio video data, and the time codeinformation corresponding to the source audio data are described in theauxiliary data area of the encoded audio stream.
 7. A data transmissionsystem according to claim 1, wherein the time code information includesa longitudinal time code/linear time code (LTC) and a vertical intervaltime code (VITC).
 8. A data transmission method comprising the steps of:supplying source audio data, source video data and time code informationattached to the source video data from a first recording medium, whereinthe time code information is associated with each video frame of saidsource video data; generating an encoded stream having a first audiostream encoded in accordance with a moving pictures expert group (MPEG)standard, a second audio stream encoded in accordance with a standarddifferent from the MPEG standard, and a plurality of layers generated byencoding the source video data, and for describing the time codeinformation attached to each frame of the source video data into apicture layer among the plurality of layers; transmitting the encodedstream; decoding the transmitted encoded stream and extracting the timecode information from the picture layer of the encoded stream by parsingthe syntax of the encoded stream; and recording the decoded data and theextracted time code information in a manner associated with each otheronto a second recording medium so as to obtain the same data as on thefirst recording medium.
 9. A data transmission method according to claim8, wherein the plurality of layers of the encoded stream include asequence layer, a GOP layer, the picture layer, a slice layer, and amacroblock layer.
 10. A data transmission method according to claim 9,wherein: a data element defined by a sequence_header ( ) function, adata element defined by a sequence_extention( ) function and a dataelement defined by an extention_and_user_data(0) are described in thesequence layer; a data element defined by a group_of_picture_header( )function and a data element defined by an extention_and_user_data(1) aredescribed in the GOP layer; a data element defined by a picture_header() function, a data element defined by a picture_coding_extention( )function and a data element defined by an extention_and_user_data(2) aredescribed in the picture layer; and the time code information is definedby a time_code( ) function indicated by a user_data( ) functionindicated by an extention_and_user_data(2) function.
 11. A datatransmission method according to claim 8, wherein the time codeinformation is data described in the user data area of the picture layerand a marker bit is inserted therein at predetermined intervals so thatthe time code information may not be mistaken for a unique start codecontained in the encoded stream when analyzing the encoded stream.
 12. Adata transmission method according to claim 8, wherein time codeinformation associated with each frame of the source audio data isattached to the source audio data and wherein the time code informationattached to each frame of the source audio data is described in theauxiliary data areas of the encoded first and second audio streams. 13.A data transmission method according to claim 12, wherein phaseinformation indicating a phase difference between a respective frame ofthe source video data and the corresponding frame of the audio data, andthe time code information corresponding to the source audio data aredescribed in the auxiliary data area of the encoded audio stream.
 14. Adata transmission method according to claim 8, wherein the time codeinformation includes a longitudinal time code/linear time code (LTC) anda vertical interval time code (VITC).